This application claims the priority of German Patent Document 100 05 010.7, filed in Germany on Feb. 4, 2000, the disclosures of which is expressly incorporated by reference herein.
The invention relates to a method for restraining an occupant on a vehicle seat and to a safety restraint device for restraining the occupant on a vehicle seat during a traffic accident.
Safety restraint systems are now fitted to most seats in motor vehicles. They serve to minimize injuries to occupants if the vehicle is involved in an accident. Active systems such as, in particular, safety belts and so-called airbags are used in this context nowadays.
Safety belts have been used in motor vehicles for a long time now. There are therefore also many different types of so-called belts used to ensure the safety of people in vehicles. Thus, for example, many vehicles are fitted with commercially available belts which are arranged at either two or three fixing points in the vehicle and are intended to prevent the bodies of the people in the vehicle from flying forwards due to inertia if the vehicle suddenly brakes sharply or strikes an obstacle.
If a vehicle strikes an obstacle, especially at high speed, the occupants are thrown forwards due to inertia. If no safety devices have been fitted, such accidents generally result in severe and, in some cases, fatal injuries to people in the vehicle. If the vehicles"" equipment includes safety belts, on the other hand, the occupants do generally have a chance of survival but injuries are frequent, especially in the area of the chest and shoulders. The reasons for this are that the occupants are often in a sitting position in which they are not resting against the backrest.
To avoid the belt being too long when there is an impact or sharp braking, German Patent Document DE-A 22 27 121 for example describes a restraining belt system in which use is made of a belt tensioner that pulls the seat belt back when the vehicle is involved in a collision. This makes it possible to ensure that the occupant is in the most favorable sitting position for him during the impact.
German Patent Document DE 44 11 184 (corresponding U.S. Pat. No. 5,552,986) describes a restraining belt system in which a tightening force exerted on the seat belt is controlled in three steps. With the aid of a so-called pretensioner, the seat belt is namely tensioned only up to a predetermined pretensioning force before a vehicle collision, this pretensioning force then invariably being relaxed in a second step if the expected vehicle collision against which this precaution has been taken does not occur. In a third step, the additional belt tensioner will pull the seat belt back at a higher pretensioning force, this occurring when an actual vehicle collision is detected.
German Patent Document DE-A 2 159 265 (corresponding U.S. Pat. No. 3,838,746) has described a restraint device in which a pretension on the holding belts is built up when the brake is actuated. At the moment of collision, the belts are thus resting on the body of the occupant with a pretension that is still tolerable.
European Patent Document EP 0 560 181 describes a driving device for moving motor-vehicle components from a normal position into a safety position. The sensor used for this responds to an excessive change in the speed of the vehicle, after which a gas generator arranged in a piston releases a pressurized gas by ignition and thereby drives the piston, by means of which the safety-belt restraint system can then be activated, for example.
In the holding system for motor vehicle occupants described in German Patent Document 22 49 759 C2 (corresponding U.S. Pat. No. 3,918,545), the safety belt is tensioned above a predefined acceleration threshold, and the magnitude of the pretensioning force is set as a function of the change in vehicle speed per unit time and/or the weight of the occupant.
However, all these safety systems known from the prior art have the disadvantage that the belt slack is removed by a pretensioning system before an accident but the belt force is not adapted to the sitting position, and the load on the occupant is therefore high.
Starting from this known prior art, an object on which the invention is based is to provide a method and a safety restraint device for restraining an occupant on a vehicle seat by means of which it is possible to minimize the loads on the occupant when pretensioning the belt slack but, at the same time, to set it at a required level.
This object is achieved according to preferred embodiments of the invention by providing a method and system for restraining an occupant on a vehicle seat, comprising:
pulling the occupant into the vehicle seat with a predetermined pullback force by a belt tensioner when a critical driving state is detected, and
subsequently holding the occupant in a pulled-back position on the vehicle seat with a predetermined holding force,
wherein the predetermined holding force is lower than the predetermined pullback force.
With the solution according to the invention, the occupants in a vehicle, especially the front seat passenger, who is not always in a position completely towards the back and may even be leaning forwards (out of position), are first of all pulled back into the seat with a certain force and are then held with a holding force, which can be chosen to be lower, during the critical vehicle state.
This advantageously makes it possible to minimize any possible injuries to the occupants with safety systems.
This method according to the invention can be implemented, in particular, by means of a safety restraint device according to the invention for restraining the occupant on a vehicle seat during a critical driving state, in which the safety belt, a belt tensioner or the like is subjected to a force in the event of a dangerous driving state, the occupant thereby first of all being pulled into the vehicle seat and then held in a pulled-back position on the vehicle seat with a lower holding force.
An apparatus of this kind has proven advantageous for carrying out a method according to the invention in all imaginable critical driving states. Examples are full braking or a vehicle impact, rollover or when the vehicle swerves or slides sideways. By restraining the occupant before an accident, it is namely not only possible to reduce the risk of injury, as described above, but, especially in the case of swerving, there is the fact that the driver is held in a safe position on the seat during the critical state. Secured in this way, the driver can thus maneuver the vehicle more effectively and hence actively contribute to stabilization of the driving state.
Further advantages, advantageous refinements and developments of the invention will emerge from the subclaims and the exemplary embodiments explained below with reference to the drawing, the drawing showing preferred embodiments of the method according to the invention and the safety restraint device for restraining an occupant on a vehicle seat.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.